For a very long time, people have read paper books. Nowadays, due to development of electronic technology, people can read electronic books via a display.
However, a traditional display device displays a literal image by using a backlight source to illuminate, which is prone to visual fatigue. Thus, it is not suitable to be read for a long time by a reader. In addition, the traditional display device such as a cold cathode ray tube display device and a liquid crystal display device has a shortcoming of continuous power consumption. Therefore, recently, an electronic paper display device has been developed due to its advantages of lightness, thinness and low power consumption.
The electronic paper display device is based on an electrophoresis principle. Charged pigment particles in the electronic paper display device are driven by an electric field to move, thereby achieving a color contrast to display an image. The electronic paper display device has low power consumption because its bistable property. In addition, the electronic paper display device has a wide viewing angle. The familiar electronic paper display device is, for example, a microcapsule electronic paper display device or a microcup electronic paper display device.
Referring to FIG. 1, a typical microcapsule electronic paper display device 1 includes an electronic paper 11 and a driving substrate 12.
The electronic paper 11 includes a lower substrate 111, an upper substrate 112 facing to the lower substrate 111, and an electrophoretic material E disposed between the upper substrate 112 and the lower substrate 111. A common electrode 113 is fixed to the upper substrate 112 and faces to the lower substrate, and a number of pixel electrodes 121 are disposed on the driving substrate 12. The common electrode 113 is cooperated with the pixels electrodes 121 to form a number of electric fields. The electrophoretic material E includes a number of light color pigment particles C1 and a deep color medium solution L1. The pigment particles C1 and the medium solution L1 both are received in a number of microcapsule E1 respectively. The microcapsule E1 can be adhered to each other by an adhesive.
For example, when an electric field is generated between a pixel electrode 121 and the common electrode 113 (i.e., the pixel electrode 121 is driven), the charged light color pigment particles C1 are driven to move near to the upper substrate 112 of the typical microcapsule electronic paper display device 1. The charged light color pigment particles C1 reflect an external light, thereby displaying the light color of the pigment particles C1 at a pixel position corresponding to the pixel electrode 121. When no electric field is generated between a pixel electrode 121 and the common electrode 113 (i.e., the pixel electrode 121 is not driven), the charged light color pigment particles C1 are located near to the lower substrate 111 of the typical microcapsule electronic paper display device 1. The deep color medium solution L1 reflect an external light, thereby displaying the deep color of the medium solution L1 at a pixel position corresponding to the pixel electrode 121. By controlling one portion of the pixel electrodes 121 of the typical microcapsule electronic paper display device 1 to be driven and controlling another portion of the pixel electrodes 121 of the typical microcapsule electronic paper display device 1 not to be driven, the typical microcapsule electronic paper display device 1 can display an image. Even if the power was cut off, the typical microcapsule electronic paper display device 1 still can display an image displayed in the last driven state. In other words, when people use the typical microcapsule electronic paper display device 1, the power consumption is very low.
Referring to FIG. 2, a typical microcup electronic paper display device 2 includes an electronic paper 21 and a driving substrate 22. The electronic paper 21 includes an upper substrate 211, a common electrode 212 fixed to the upper substrate 211, a microcup layer 213 and a lower substrate 214.
The typical microcup electronic paper display device 2 is similar to the typical microcapsule electronic paper display device 1 except that the structure of the electronic paper 21. The microcup layer 213 of the typical microcup electronic paper display device 2 is configured for receiving the electrophoretic material E. It is noted that, the electrophoretic material E of the typical microcapsule electronic paper display device 1 is received in the microcapsule E1. The microcup layer 213 is made of a polymer resin and is formed by using a roll-to-roll process. The microcup layer 213 includes a number of cavities for receiving a number of charged light color pigment particles C2 and a deep color medium solution L2. After the charged light color pigment particles C2 and the deep color medium solution L2 are filled, the cavities of the microcup layer 213 is sealed. The microcup layer 213 can be adhered to the upper substrate 211 via an adhesive layer. By controlling the pixel electrodes 221 of the driving substrate 22 to be driven or not to be driven, the typical microcup electronic paper display device 2 can display an image.
With development of the electronic paper display technology, the resolution of the electronic paper display device is continuously increased so that the electronic paper display device can be widely applied. However, the current structure of the driving substrate 12/22 and the current fabricating process of the driving substrate 12/22 limit the development of the electronic paper display device. For example, the typical microcapsule electronic paper display device 1 and the typical microcup electronic paper display device 2 may display the borders or the shadow lines of a number of conductive wires connected to the pixel electrodes 121/221, which is not hoped to be displayed. As a result, the resolution of the electronic paper display device is limited and can not be increased continuously.